Main Power Supply and Ground Circuit Check

COMPONENT DESCRIPTION




Automatic amplifier (Auto amp.)
The auto amplifier has a built-in microcomputer which processes information sent from various sensors needed for air conditioner operation. The air mix door motor, mode door motor, intake door motor, blower motor and compressor are then controlled. The auto amplifier is unitized with control mechanisms. Signals from various switches and Potentio Temperature Control (PTC) are directly entered into auto amplifier.
Self-diagnostic functions are also built into auto amplifier to provide quick check of malfunctions in the auto air conditioner system.




A/C control unit
By means of multiplex communication, the A/C control unit sends signals to the auto amp. the switch position and display mode.




Potentio temperature control (PTC)
The PTC is built into the A/C control unit. It can be set at an interval of 0.5 °C (1.0 °F) in the 18 °C (65 °F) to 32 °C (85° F) temperature range by rotating the temperature dial. The set temperature is digitally displayed.




DIAGNOSTIC PROCEDURE

Auto amp. check







Check power supply circuit for auto amp. with ignition switch ON. Measure voltage across terminal Nos.(24), (25), (33) and body ground.







Check body ground circuit for auto amp. with ignition switch OFF. Check for continuity between terminal No.(32) and body ground.

A/C control unit check







Check power supply circuit for A/C control unit with ignition switch ON.
Measure voltage across terminal Nos. (3), (9), (10) and body ground.







Check body ground circuit for A/C control unit with ignition switch OFF.
Check for continuity between terminal No. (8) and body ground.